KR20150090169A - Hydrotreating and dewaxing process - Google Patents

Abstract

The present invention provides a process for hydrotreating and de-waxing a hydrocarbon feedstock comprising the steps of: (a) hydrotreating the feedstock under hydrotreating conditions in a first reaction zone to obtain a first hydrotreated effluent ; And (b) introducing at least a portion of the first hydrotreated effluent into a second reaction zone, wherein the first hydrotreated effluent is subjected to a series of alternating dewaxing and hydrotreating steps, Wherein the first stage of the series of alternating dewaxing and hydrotreating stages is a dewaxing step and the first stage of the alternating dewaxing and hydrotreating stages is a series of alternating dewaxing steps, The last step in the waxing and hydrotreating step is a hydrotreating step wherein the dewaxing step comprises a Group VIII metal hydride component, a dealuminated aluminosilicate zeolite crystallite, and a low acid refractory oxide binder material essentially free of alumina Step carried out with a dewaxing catalyst.

Description

[0001] HYDROTREATING AND DEWAXING PROCESS [0002]

The present invention relates to a process for the hydrotreating and de-waxing of hydrocarbon feedstocks.

It is known to prepare an ultra low sulfur diesel fuel by first hydrodesulfurizing a hydrocarbon distillate stream boiling in the light oil boiling range and then catalytically dewaxing the desulfurized distillate stream. The catalytic de-waxing step is necessary to remove waxy molecules from the distillate stream to reduce the cloud point and pour point of the light oil. The desulfurized and dewaxed light oil may be hydrofinished to saturate the aromatics. The resulting desulfurization, dewaxing and optionally hydrogenation-finished light oil are then used as diesel fuel or diesel fuel components.

Also in the production of lubricating oil, the dewaxing step is carried out to reduce the pour point of the lubricating oil being produced.

The catalytic dewaxing step is usually carried out in a first stage dewaxing process or a second stage dewaxing process.

In the so-called first de-waxing process, the light oil is first applied to at least one hydrotreating step, followed by a first de-waxing step, followed by an additional hydrotreating step. In this first de-waxing step, a base metal catalyst such as a mesoporous zeolite support is used, for example a nickel-containing catalyst on ZSM-5.

In the second stage dewaxing process, the light oil is first applied to at least one hydrotreating stage followed by a second stage dewaxing step carried out using a noble metal-based catalyst on medium or large pore zeolite. Most of today's catalytic dewaxing processes are carried out in a first stage dewaxing mode of operation. In the hydrotreating step of this first de-waxing process, a portion of the heteroatom species is removed from light oil and the aromatics are saturated. The so obtained effluent is then de-waxed in the de-waxing stage and the aromatic and hetero-atom species still present in the de-waxed light oil can be removed by a subsequent hydrotreating step. Also, if all three process steps are carried out in a stacked bed arrangement, the disadvantage of this process arrangement is that the hydrotreating step is exothermic, while the de-waxing step is often quite endothermic, Temperature control is difficult.

It is an object of the present invention to provide an improved hydrotreating and de-waxing process.

SUMMARY OF THE INVENTION

This object is achieved when the hydrogenation and dewaxing steps in a particular order (in which a specific catalyst is applied in the dewaxing step) is used.

Accordingly, the present invention relates to a process for hydrotreating and de-waxing hydrocarbon feedstocks boiling in the range of 170-450 占 폚, comprising the steps of:

(a) hydrotreating the feedstock under hydrotreating conditions in a first reaction zone to obtain a first hydrotreated effluent; And

(b) introducing at least a portion of the first-stage hydrotreated effluent into a second reaction zone, wherein the first hydrotreated effluent is subjected to a series of alternating dewaxing and hydrotreating steps, wherein the dewaxing Wherein the hydrotreating step is carried out under catalytically de-waxing conditions, the hydrotreating step is carried out under hydrotreating conditions, the first of the series of alternating dewaxing and hydrotreating steps is a dewaxing step and a series of alternating dewaxing The final step in the hydrotreating and hydrotreating step is a hydrotreating step wherein the dewaxing step is carried out in the presence of a Group VIII metal of the Periodic Table of the Elements, a dealuminated aluminosilicate zeolite crystallite, and a degassed refractory oxide binder material essentially free of alumina A step carried out with a waxing catalyst.

According to the present invention, improved temperature control for the reaction end is obtained, while at the same time less dewaxing catalyst is required.

DETAILED DESCRIPTION OF THE INVENTION

In the second reaction zone, a number of hydrotreating steps and a number of dewaxing steps are carried out in step (b). Suitably, in step (b) at least three hydrotreating steps and at least three dewaxing steps are carried out. Preferably, in step (b), three hydrotreating steps and three dewaxing steps are carried out. In this embodiment, the first stage effluent in the second reaction zone is then subjected to a first dewaxing step, a first hydrotreating step, a second dewaxing step, a second hydrotreating step, a third dewaxing step, and a third hydrotreating step do.

The hydrocarbon feedstock boils in the range of 170 to 450 占 폚, preferably 170 to 400 占 폚.

Examples of the hydrocarbon feedstock to be used in accordance with the present invention are direct current diesel, hydrogenolysis light oil, pyrolysis light oil, coker light oil, vacuum light oil, light or heavy cycle oil, or a combination of two or more thereof. Suitably, the hydrocarbon feedstock is solvent extracted wax raffinate. Preferably, the hydrocarbon feedstock is light oil.

Such hydrocarbon feedstocks typically contain sulfur-containing compounds, typically at concentrations ranging from a few hundred ppm to some percent of sulfur. Reference herein to light oil or hydrocarbon streams boiling in the light oil boiling range is a hydrocarbon stream boiling in the light oil boiling range of at least 90 wt%, preferably at least 95 wt% thereof, ranging from 170 to 450 캜 .

The hydrotreating catalyst to be used in the first reaction zone in step (a) may suitably be a desulphurisation catalyst. The desulfurization catalyst may be any desulfurization catalyst known in the art. Suitably, the hydrotreating catalyst comprises a metal and / or a metal compound of Group VIII of the Periodic Table of the Elements and a metal and / or a metal compound of Group VIB of the Periodic Table of the Elements. Typical desulfurization catalysts include compounds of the Group VIII metals of the Periodic Table of the Elements and the Group VIB metals of the Periodic Table of Elements as hydrogenated components on porous catalyst supports, usually alumina or amorphous silica-alumina. Well known examples of suitable combinations of hydrogenated compounds are cobalt-molybdenum, nickel-molybdenum, nickel-tungsten, and nickel-cobalt-molybdenum. A hydrodesulphurisation catalyst comprising nickel and / or a compound of cobalt and molybdenum as the hydrogenation compound is preferred. The hydrodesulfurization catalyst may further comprise a cracking component such as, for example, a Y zeolite. However, it is preferred that no substantial hydrocracking takes place in the hydrodesulfurization step (a) of the process according to the invention. Therefore, it is preferable that the catalyst is substantially free of decomposition components. Catalysts comprising nickel and / or cobalt and molybdenum supported on alumina without zeolite decomposition compounds are particularly preferred.

The conditions of hydrotreating in step (a), i.e., temperature, pressure, hydrogen feed rate, and weight hourly rate of feedstock, are typical hydrotreating conditions. Preferably, the temperature in the hydrotreating step is in the range of 280 to 420 占 폚, more preferably in the range of 300 to 400 占 폚, and most preferably in the range of 320 to 390 占 폚.

Suitable hydrotreating pressures range from 10 to 200 bara. Preferably, the hydrotreating pressure is in the range of 15 to 100 bara, more preferably in the range of 20 to 80 bara.

The exact hydrotreating conditions in step (a) depend, in particular, on the catalyst used, the sulfur content of the hydrocarbon feedstock, the desired conversion of the sulfur- and nitrogen-containing compounds, and the extent of hydrocracking of the hydrocarbons boiling above 370 DEG C Will be different. Preferably, up to 10% by volume of hydrocarbon feedstock boils above 370 DEG C are hydrogenated with low boiling compounds. Preferably, the first stage effluent has a sulfur content of at most 150 ppmw, more preferably at most 40 ppmw, even more preferably at most 20 ppmw, even more preferably at most 10 ppmw, particularly preferably at most 5 ppmw . The nitrogen content of the first stage effluent is preferably at most 50 ppmw, more preferably at most 10 ppmw, even more preferably at most 1 ppmw.

It is within the skill of the art to select the hydrotreating conditions in step (a) in such a manner that the desired sulfur and nitrogen conversion is achieved.

In step (a), most of the sulfur- and nitrogen-containing compounds present in the hydrocarbon feedstock are each converted to hydrogen sulphide and ammonia, respectively. In step (a), the hydrogen and the hydrocarbon feedstock may be fed in the same or opposite direction as the first reaction zone, preferably in the same direction. If hydrogen and liquid hydrocarbon feedstock are fed in the same direction in the first reaction zone, it will be appreciated that the vapor-liquid mixture is obtained as the first stage effluent. Optionally, the first stage effluent can be separated into liquid and vapor effluent. The separation can be carried out by any method known in the art, for example by using a vapor / liquid separator, such as a draw-off tray, by stripping in a separator-stripper or after vapor / liquid separation And stripping of the liquid phase so obtained for the removal of dissolved hydrogen sulfide and ammonia. If step (a) is carried out in the opposite direction, the vapor effluent will be discharged from the top of the first reaction zone and the liquid effluent will be recognized as being discharged from the bottom of the reaction zone. In this case, the liquid effluent as effluent from the first reaction zone can be in direct contact with the loading layer of the dewaxing and hydrotreating catalyst in step (b). Optionally, the dissolved gas is removed from the liquid effluent, typically by stripping, and then the liquid effluent is contacted with the loading layer of the dewaxing and hydrotreating catalyst in step (b).

In step (b) of the process according to the invention, the first stage effluent is subjected to a series of dewaxing and hydrotreating steps. The first stage effluent is first applied to the de-waxing step by contacting it with the de-waxing catalyst under de-waxing conditions, i.e., at elevated temperature and pressure and in the presence of hydrogen. The hydrogen is preferably fed to the loading layer of the catalyst in the second reaction zone in the same or opposite direction, preferably in the same direction, for the first stage effluent.

In step (b), a number of catalytic dewaxing steps are applied. Suitably, in step (b), at least three dewaxing steps are applied. Preferably, in step (b), three de-waxing steps are applied.

Catalytic de-waxing refers to a method of reducing the pour point or cloud point by selectively selectively converting a component of the oil feed that imparts a high pour point or cloud point to a product that does not confer high pour point or cloud point. The product giving a high pour point or point is a compound with a high melting point. The compound is referred to as a wax. Wax compounds include, for example, high temperature molten paraffin, iso-paraffin, and mono-ring compounds. The pour point or cloud point is preferably reduced by at least 10 캜, more preferably by at least 20 캜. It has been found possible to reduce the turnover and pour point above 30 ° C, which is very advantageous when producing some winter grade diesel (diesel) fuels.

The dewaxing step in step (b) comprises catalytic dewaxing using a catalyst composition comprising a Group VIII metal hydride component, a dealuminated aluminosilicate zeolite crystallite, and a low acid refractory oxide binder material essentially free of alumina Lt; / RTI > In the context of this application, the term "essentially free of alumina" means that the low acid refractory oxide binder material comprises less than 95 wt%, preferably less than 99 wt% alumina, based on the total weight of the low acid refractory oxide binder material . More preferably, the low acid refractory oxide binder material has no alumina.

This type of dewaxing catalyst has been found to be very stable over time, even though a high amount of sulfur is present in the oil feed. Examples of such catalysts are described in WO-A-9641849. In addition, it has been found that much less coke is formed when using this type of catalyst when compared to a catalyst containing an alumina-based binder material.

The aluminosilicate zeolite crystallites preferably have a pore diameter in the range of 0.35 to 0.80 nm. More preferably, the aluminosilicate zeolite crystallites have voids containing 10 oxygen atoms. The diameter is referred to as the maximum pore diameter. As is generally recognized, voids in a molecular sieve are polygonal shaped channels with minimum and maximum pore diameters. For purposes of the present invention, the maximum pore diameter is a critical parameter since it determines the size of the waxy molecules that can be introduced into the pores. More preferably, the zeolite crystallites have a Constraint Index of from 2 to 12. The constraint index is a measure of the extent to which zeolites provide control over molecules of varying size to their internal structure being zeolite. A zeolite providing a highly constrained access and its escape to its internal structure has a high value for the constraint index. On the other hand, zeolites providing a relatively free access to internal zeolite structures have low values for the constraint index, and usually have large pores. A method of measuring the constraint index is described in detail in US-A-4016218, the details of which are incorporated herein by reference. Examples of aluminosilicate zeolites having a constraint index of from 2 to 12 and suitable for use in the present invention include ferrierite, ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM- ZSM-35, ZSM-38, ZSM-48, ZSM-57, SSZ-23, SSZ-24, SSZ-25, SSZ-26, SSZ-32, SSZ-33 and MCM-22. Preferred aluminosilicate zeolites are of MFI-topology, for example ZSM-5.

Crystallite size of zeolite can be as high as 100 microns. The crystallite size of individual particles can be measured using high resolution scanning electron microscopy. The size of the crystallite is the longest or predominant aspect of the particle.

Preferably, a small crystallite is used to achieve optimal catalytic activity. Crystallites preferably smaller than 10 microns, more preferably smaller than 1 micron are used. The practical lower limit is suitably 0.1 micron.

The dewaxing catalyst used in the dewaxing step in step (b) also comprises a low acid refractory oxide binder material essentially free of alumina.

Examples are low acid refractory oxides such as silica, zirconia, titanium dioxide, germanium dioxide, boria and mixtures of two or more thereof. The most preferred binder is silica. The weight ratio of modified molecular sieve to binder is suitably in the range of 05/95 to 95/05.

The dealumination of the aluminosilicate zeolite results in a reduction in the number of alumina fractions present in the zeolite and thus a reduction in the mole percentage of alumina. The expression "part of alumina" as used in connection therewith is a part of the framework of the aluminosilicate zeolite, that is, introduced into the framework of the aluminosilicate zeolite through the covalent bond with another part of the oxide, such as silica (SiO ₂ ) , And Al ₂ O ₃ - units. The molar percentage of alumina present in the aluminosilicate zeolite is the molar amount of Al ₂ O ₃ to the total number of moles of the oxides constituting the aluminosilicate zeolite (before dealumination) or the modified molecular sieve (after dealumination) .

Preferably, the surface of the zeolite crystallite is selectively dealuminated. Selective surface dealumination does not affect the internal structure of the zeolite crystallites, while yielding a reduction in the number of surface acid sites on the zeolite crystallites.

The dealumination can be accomplished by methods known in the art. Particularly useful methods are those which are claimed to occur selectively on the surface of the crystallites of the molecular sieve, whatever the dealumination occurs selectively or whatever. An example of a dealumination process is described in the above-mentioned WO-A-9641849.

Preferably, the dealumination is carried out by a process wherein the zeolite is contacted with an aqueous solution of a fluorosilicate salt, said fluorosilicate salt being represented by the formula:

(A) _{2 / b} SiF ₆

(Wherein A is a metallic or non-metallic cation other than H + having a valence of b). This treatment will also be referred to as AHS treatment. Examples of cations 'b' are ^{alkylammonium, NH 4+, Mg ++, Li} +, Na +, K +, Ba ++, Cd ++, Cu +, Ca ++, Cs +, Fe ++, Co ⁺⁺ , Pb ⁺⁺ , Mn ⁺⁺ , Rb ⁺ , Ag ⁺ , Sr ⁺⁺ , Tl ⁺ , and Zn ⁺⁺ . Preferably 'A' is an ammonium cation. The zeolite material may suitably be contacted with the fluorosilicate salt at a pH of from 3 to 7. This dealumination process is described, for example, in US-A-5157191. The dealumination process is referred to as AHS-treatment.

The dewaxing catalysts to be used according to the invention are preferably prepared by first extruding the aluminosilicate zeolite with a binder and then applying the extrudate to a dealumination treatment, preferably to the AHS treatment as described above do. It has been found that the increased mechanical strength of the catalyst extrudate is obtained when prepared according to the steps of the above sequence.

The Group VIII metal of the Periodic Table of the Elements is suitably added to the catalyst extrudate comprising the dealuminated aluminosilicate zeolite crystallites by known techniques, such as ion-exchange techniques.

A typical ion-exchange technique refers to contacting the selected zeolite with the salt of the desired cation. A wide range of salts may be used, but particularly preferred are provided as chloride, nitrate and sulfate. Representative ion-exchange techniques are described in a wide range of patents including US-A-3140249, US-A-3140251 and US-A-3140253.

A dewaxing catalyst comprising a Group VIII metal hydride component is used in the dewaxing step. Group VIII metal components include the components described in precious metals and non-precious metals.

Suitable Group VIII metal components are thus palladium, platinum, nickel and / or cobalt in sulfide, oxide and / or elemental form. Preferably, the dewaxing catalyst comprises nickel in the form of sulphide, oxide and / or element. The total amount of the Group VIII metal of the Periodic Table of Elements is suitably calculated as an element and will not exceed 10% by weight, preferably in the range of 0.1 to 5.0% by weight, more preferably in the range of 0.2 to 3.0% by weight, . The Group VIII metal hydride component is preferably nickel.

The catalytic dewaxing conditions in step (b) of the process according to the invention are typical catalytic dewaxing conditions. Accordingly, the temperature is suitably in the range of 250 to 420 占 폚, preferably 280 to 420 占 폚, more preferably 300 to 400 占 폚. Suitable dewaxing pressures range from 10 to 200 bara.

Preferably, the de-waxing pressure is in the range of 15 to 100 bara, more preferably in the range of 20 to 80 bara. The dewaxing step is carried out in the presence of hydrogen. The hydrogen is suitably fed to the second reaction zone at a rate of between 250 and 750 Nl / kg.

A number of hydrotreating steps are applied in step (b). Suitably at least two hydrotreating steps are applied in step (b). Preferably, in step (b) three hydrotreating steps are applied. Preferably, the temperature in the hydrotreating step is in the range of 280 to 420 占 폚, more preferably in the range of 300 to 400 占 폚, and most preferably in the range of 320 to 390 占 폚. Suitable hydrotreating pressures range from 10 to 200 bara. Preferably, the hydrotreating pressure is in the range of 15 to 100 bara, more preferably in the range of 20 to 80 bara.

In the hydrotreating step in step (b), the heteroatom species still present in the first stage effluent is at least partially removed. Also, at least a portion of the aromatics still present in the dewaxed first stage effluent are saturated. In a preferred embodiment of the present invention, a base metal catalyst, such as nickel-molybdenum, is used on the alumina support in the hydrotreating step in step (b).

The loading layer of the catalyst applied in the second reaction zone in step (b) is preferably a first layer comprising a dewaxing catalyst, a second layer comprising a hydrotreating catalyst, a third layer comprising a dewaxing catalyst, A fourth layer comprising a catalyst, a fifth layer comprising a dewaxing catalyst, and a sixth layer comprising a hydrotreating catalyst. Suitably, similar hydrotreating catalysts are used in the second, fourth and sixth layers.

The particular order of catalyst layers applied to step (b) is to provide improved temperature control for the reaction stages since large temperature variations between the layer comprising the dewaxing catalyst and the catalyst layer comprising the hydrotreating catalyst can be avoided .

Besides the improved temperature control, the main advantage is that it is surprising that a total de-waxing catalyst is needed in the separation catalyst layer, in total, less than the total amount of dewaxing catalyst typically required in a single layer to obtain similar performance in the first dewaxing stage It is true. According to the present invention, a reduction of 20-25% or less of the total volume of the dewaxed catalyst can be achieved.

Preferably, the temperatures in the different catalyst beds in the second reaction zone are the same. However, it is also very interesting to operate the hydrotreating step and the dewaxing step at only a slight difference in temperature. For example, the dewaxing step may be carried out at a temperature which is 5 to 30 ° C lower than the temperature at which the hydrotreating step is carried out in step (b). A quench inserted between the catalyst beds can be used to cool the first stage effluent. This can be advantageous if only limited dewaxing is required.

The loading layers of the catalyst can be made up of a single layer of de-waxing and hydrotreating catalyst, without spacing on top of each other, i.e. between the six layers.

Alternatively, the six layers may be spaced. Each of the six layers can be divided into consecutive separation layers.

In the case of two or more spaced layers, it is possible for the inserted cooling to remove the heat released during the exothermic hydrotreating step, for example by an inserted quench.

The first reaction zone and the second reaction zone may be arranged in the same reactor or in separate reactor vessels. Preferably, the first reaction zone and the second reaction zone are both located in the same reactor vessel, whereby the first reaction zone is arranged upstream with respect to the second reaction zone.

Preferably, the volume of each of the catalyst beds in which each hydrotreating step is carried out is less than the volume of each of the catalyst beds in which each de-waxing step is carried out. More preferably, the total volume of the layer of the hydrotreating catalyst is in the range of 10 to 65% of the total volume of the layer of the dewaxing catalyst.

Reference herein to the volume of the layer of the hydrotreating catalyst is for the total volume of the layer without the inserted space. The same applies to the volume of the layer of dewaxing catalyst with slight modification.

In the process according to the invention, preferably the entire first stage effluent of the first reaction zone is introduced into the second reaction zone.

The boiling point of the second stage effluent as obtained in step (b) is in the range of 10 to 20 占 폚 lower than the boiling point of the first stage effluent as obtained in step (a).

The second stage effluent as obtained in step (b) can suitably be transported directly into the diesel fuel blending pool, i.e. without further treatment. Reference herein to treatment refers to a process in which the molecular structure of the light oil component changes and thus excludes blending.

The second stage effluent can be separated into a gaseous fraction and a liquid fraction. Such separation or fractionation can be obtained by conventional methods such as by distillation under atmospheric pressure or reduced pressure. Of these, distillation under reduced pressure including vacuum flash and vacuum distillation is most suitably applied. The cutpoint of the distillate fraction (s) is selected such that each product distillate recovered has the desired properties for its contemplated application.

In the process according to the invention, hydrotreated and dewaxed light oil is obtained which is very suitable for use as a diesel fuel in a cooling environment, for example in winter. In summer, this may not always be necessary to reduce the pour point and cloud point of the hydrotreated diesel, but it may be desirable to hydrogenate the diesel to improve aromatic saturation or cetane or density. It is an advantage of the process according to the invention that the equipment required for the process (hardware including catalyst) can also be used to operate in the so-called summer mode. Said so-called summer operation is similar to the process according to the invention except that the catalyst bed in the second reaction zone in step (b) is kept at a low temperature, i.e. a temperature at which de-waxing does not occur. This can be accomplished, for example, by quenching the first stage effluent as obtained in step (a). In this way, the hydrocarbon feedstock will only be hydrotreated and not de-waxed. Thus, a light oil suitable for transporting to the diesel fuel blending pool for summer-grade diesel fuel is obtained. It is specified that the summer-mode operation described above is not a process according to the present invention.

The invention will be illustrated by the following non-limiting examples.

Example 1 (according to the invention)

Hydrocarbon feedstocks having the properties listed in Table 1 were heated at a temperature of 349 DEG C, an outlet pressure of 70 bara, a weight hourly space velocity (WHSV) of 0.71 kg / l.hr and a once through of 341 Nl / kg ) Gas velocity in the presence of hydrogen with the hydrotreating catalyst in the first reaction zone. The hydrotreating catalyst is DN3531 (ex-Criterion) containing nickel-molybdenum on an alumina support.

Table 1

(IBP), T50 and final boiling point (FBP) by NF T 60-105, kinematic viscosity by NF-EN-ISO 3104, sulfur by ASTM D 5453, nitrogen by SMS 2695m And the content thereof was measured.

The first stage effluent thus obtained is introduced into a second reaction comprising six catalyst beds in a stacked bed arrangement. The first, third and fifth layers contained a dewaxing catalyst, while the second and fourth and sixth layers contained a hydrotreating catalyst. The volume of catalyst used is shown in Table 2. The hydrotreating catalysts used in the second, fourth and sixth layers include DN-3531 (ex-Criterion) containing nickel-molybdenum on an alumina support. The de-waxing catalyst used in the first, third and fifth layers comprises a nickel-based catalyst, SDD 800 (ex-Criterion).

The reaction conditions applied to the six layers are shown in Table 2. The properties of the products obtained from the hydrotreating zone are given in Table 3.

Table 2

Table 3

Example 2 (Comparative Example)

The hydrotreating and dewaxing process was carried out as follows. The hydrocarbon feedstock described in Example 1 was heated at a temperature of 349 占 폚, an outlet pressure of 70 bara, a weight hourly space velocity (WHSV) of 0.71 kg / l.hr, and a once through gas velocity of 341 Nl / kg With the hydrotreating catalyst in the presence of hydrogen in the first reaction zone. The hydrotreating catalyst was the same catalyst as used in the first reaction zone in Example 1.

The first stage effluent thus obtained is introduced into a second reaction comprising two catalyst beds in a stacked bed arrangement. The first layer contained a dewaxing catalyst, while the second layer contained a hydrotreating catalyst. The hydrotreating catalyst and de-waxing catalyst used were the same as those applied in the second reaction zone in Example 1. The volume of catalyst used is shown in Table 4. The reaction conditions applied to the five layers are shown in Table 4. The properties of the products obtained from the second reaction zone are given in Table 5.

Table 4

Table 5

From the above results it will be clear that according to the present invention the temperature is more interestingly adjusted for the various stages in the first and second reaction zones while at the same time requiring fewer dewaxing catalysts for use in obtaining products of comparable character .

Claims (15)

A process for hydrotreating and de-waxing a boiling hydrocarbon feedstock within the range of 170-450 占 폚, comprising the steps of:
(a) hydrotreating the feedstock under hydrotreating conditions in a first reaction zone to obtain a first hydrotreated effluent; And
(b) introducing at least a portion of the first-stage hydrotreated effluent into a second reaction zone, wherein the first hydrotreated effluent is subjected to a series of alternating dewaxing and hydrotreating steps, wherein the dewaxing Wherein the hydrotreating step is carried out under catalytically de-waxing conditions, the hydrotreating step is carried out under hydrotreating conditions, the first of the series of alternating dewaxing and hydrotreating steps is a dewaxing step and a series of alternating dewaxing The final step in the hydrotreating and hydrotreating step is a hydrotreating step wherein the dewaxing step is carried out in the presence of a Group VIII metal hydride component, a dealuminated aluminosilicate zeolite crystallite and a degassed refractory oxide binder material essentially free of alumina A step carried out with a waxing catalyst. The method of claim 1 wherein three hydrotreating and three de-waxing steps are carried out in a second reaction zone. 3. The method of claim 1 or 2, wherein the volume of each of the catalyst beds in which each hydrotreating step is performed is less than the volume of each of the catalyst beds in which each de-waxing step is carried out. 4. The process according to any one of claims 1 to 3, wherein the hydrotreating in step (a) is carried out at a temperature in the range of 300-400 占 폚 and a pressure in the range of 20-80 bara. 5. The process according to any one of claims 1 to 4, wherein the hydrotreating step in step (b) is carried out in the presence of hydrogen at a temperature in the range of 280 to 420 DEG C and a pressure in the range of 20 to 80 bara. 6. A process according to any one of claims 1 to 5, wherein the dewaxing step in step (b) is carried out in the presence of hydrogen at a temperature in the range of 280 to 420 DEG C and a pressure in the range of 20 to 80 bara . 7. The process according to any one of claims 1 to 6, wherein the Group VIII metal hydride component of the dewaxing catalyst is nickel. 8. The process according to any one of claims 1 to 7, wherein the low acid binder is silica. 9. The process according to any one of claims 1 to 8, wherein the aluminosilicate zeolite crystallite has a void comprising 10 oxygen atoms. 10. The process of claim 9 wherein the aluminosilicate zeolite crystallites are of the MFI type. 11. The process according to any one of claims 1 to 10, wherein the dealuminated aluminosilicate zeolite crystallites are obtained by contacting zeolite crystallites with an aqueous solution of a fluorosilicate salt, wherein the fluorosilicate salt is represented by the formula :
(A) _{2 / b} SiF ₆
(Wherein A is a metallic or non-metallic cation other than H + having a valence of b, preferably ammonium). 12. The method according to any one of claims 1 to 11, wherein the extrudate of the aluminosilicate zeolite crystallite and the low acid binder is contacted with an aqueous solution of a fluorosilicate salt. The method according to any one of claims 1 to 12, wherein the hydrogen treatment is carried out with a catalyst comprising a metal and / or a metal compound of Group VIII of the Periodic Table of the Elements and a metal and / or a metal compound of Group VIB of the Periodic Table of the Elements . 14. The process according to any one of claims 1 to 13, wherein the hydrocarbon feedstock boils in the range of 170-450 占 폚. 15. The process according to any one of claims 1 to 14, wherein the hydrocarbon feedstock is gas oil.